1. Field of the Invention
This invention generally relates to shotshells and more particularly to a water resistant shot wad/shot cup, and preferably to such a wad/cup for steel shot loads.
2. Description of the Related Art
Shotshells for water fowl hunting have increasingly utilized steel shot loads to avoid the alleged toxicity problems claimed to be associated with lead shot. Waterfowl hunting is normally done near the water. Duck hunting is normally done from a duck blind or a boat and often in wet conditions. Accordingly, it is not unusual for shotshells to get wet during waterfowl hunting. One of the banes of waterfowl hunters is wet shotshells which fail to function properly due to wet powder. One manner in which wet powder can occur is by water penetrating the shotshell fold crimp, passing between the shot cup and the shell, then between the over-powder-cup and the shell and eventually reaching the powder charge.
Conventional shotshells, such as are described in U.S. Pat. Nos. 3,289,586; 3,469,527; 3,623,431; 3,670,650; 3,788,224; 4,220,090; 4,233,903; 4,669,385; 4,676,170; and 4,679,505 have over powder wad columns which are not waterproof or water resistant. The over powder wad is designed to provide adequate pressure sealing against forwardly directed pressure acting against the rear of the wad due to the ignition gases but is not effective to seal against low pressure rearwardly flowing water or high humidity gas entering from the front of the wad column.
One solution, for moisture exclusion in roll crimped shotshells, is to provide a sealing top wad over the shot cup as described in U.S. Pat. No. 5,138,950, assigned to the assignee of the present invention. Another is to provide a thermoplastic seal over the top of the star or roll crimp as described in U.S. Pat. No. 4,991,512, also assigned to the assignee of the present invention.
From a manufacturing point of view, it would be more desirable to provide a moisture seal which is integral with a component that normally will be installed in the shotshell such as an over powder wad or shot cup to eliminate the necessity for providing an additional component to the shotshell. In addition, from a shooter's standpoint, it is preferable to seal from behind the shot so as to avoid having any extra components in front of the shot which might interfere with the shot patterning or clog gas ports of semi-automatic shotguns. However, there is no existing shotshell which has this ability to any degree of reliability, and reliability is of overriding concern to hunters who do not want to miss their target on account of ammunition failures.
Accordingly, it is an object of the present invention to provide a reliable moisture seal behind the shot load, preferably a seal which is integral with the shot wad so as to eliminate the necessity for extra components.